Pressure sensors find wide use in industry: U.S. Pat. No. 6,452,427, U.S. Pat. No. 6,445,053, U.S. Pat. No. 6,229,190, U.S. Pat. No. 6,167,763, U.S. Pat. No. 6,112,598, U.S. Pat. No. 5,808,210, U.S. Pat. No. 5,747,705, U.S. Pat. No. 5,585,311, U.S. Pat. No. 5,535,135, U.S. Pat. No. 5,528,452, U.S. Pat. No. 5,459,351, U.S. Pat. No. 5,453,628, U.S. Pat. No. 5,155,061 U.S. Pat. No. 4,098,133, U.S. Pat. No. 4,008,619.
The topside of a typical pressure sensor includes implanted piezoresistors to convert the pressure to an electrical signal, contacts to metal interconnections and bond pads used for wire bonding. This exposes materials other than silicon that must be protected from the sensed media. A typical pressure sensor can fail if the topside protection is compromised. Such failure is common with pressure sensors. What is needed is a pressure sensor design that will reduce its failure rate.